1. Field of the Invention
The illustrated embodiments of the invention relate to an apparatus and method to provide item-level monitoring of environmental qualities or histories, including, but not limited to, temperature, humidity, air gas components, radiation.
2. Description of the Prior Art
Advancements in materials science, micro fabrication of MEMS, and bioengineered systems have made inexpensive, powerful, and ubiquitous sensing a reality. Examples range from truly smart airframes, self-evaluating buildings, and infrastructure for natural hazard mitigation to large scale weather forecasting. New detection technologies that overcome barriers of time, scale, materials, and environment, and emphasize self-calibration, selectivity, and sensitivity are required. Sensor networks that are ad hoc, multi-hop, robust, and low-power need further development. The convergence of communications, nanotechnologies, advanced materials, and information technologies with miniaturization techniques has placed sensor technology at the threshold of a period of major growth. New sensor technologies appear very promising, but unfortunately most sensors are energy hungry and have a very short battery life. The cost and maintenance of large numbers of wireless and autonomous distributed sensors has become a major issue in the micro sensor field.
For example, in the medical industry, tracking of individual items is of utter importance, particularly in the distribution of blood, organs, or other biologicals. With these items, it is further critical to monitor item level environmental variables such as temperature, shock, and humidity. For whole blood and blood components, the optimal temperature for storage has been found to be 4° C., with increased haemolysis at temperatures below 0° C. and above 10° C. Radio Frequency Identification (RFID) is a burgeoning technology that has been widely adopted to replace barcodes in inventory tracking and supply chain management. RFID permits tracking of individual units of blood (or components) through the entire cold chain and distribution network. Systems implemented with RFID showed vast improvements in patient safety from barcode tracking systems. Active and semi-passive tags have been used in hospital studies to monitor blood components, showing the utility of individual monitoring of blood units. To date, such studies have not achieved the price point necessary for individual tagging.
In the past, the cold chain management is mainly done by centralized refrigerating facilities with temperature monitoring at budding, vehicle and carton levels. For critical commodities like blood bags, there are not existing solutions to monitor individual items at relative lower cost. Currently, many institutions have a “30-minute rule” wherein blood that has been outside the blood bank for more than 30 minutes may be considered unsafe for transfusion if returned above a temperature of 10° C. Similar operator decision is involved for transportation of other commodities. Examples of relevant prior technology include: “Resettable Latching Mems Temperature Sensor Apparatus And Method” U.S. Pat. No. 7,239,064 (2005), and “Method And System For Monitoring Environmental Conditions” U.S. patent application Ser. No. 11/383,200 (2006).
The optimal temperature for the storage of whole blood and many blood components has been found to be 4° C., with increased haemolysis at temperatures below 0° C. and above 10° C. Bacterial contamination of blood and blood components has been found to be the major risk factor in transfusion medicine. In 2004, Sharma et al. found the storage conditions within the blood bank are well controlled. Blood bags that had been issued and returned, conversely, were found to have a 3.92% rate of contamination (Sharma R R, Subramanian P G, Kumar S, Singh M, Sharma M, Agnihotri S K, Marwaha N. Evaluation of storage conditions and bacterial proliferation in blood components. Lab Med 2004 October; 35(10):616-9.). This indicates a need for increased attention to conditions imparted while blood is outside the blood bank, with temperature being the most important factor.
RFID tags are available as active, passive, or semi-passive, and operate at differing frequencies depending upon the application. RFID tags are available as active, passive, or semi-passive, and operate at differing frequencies depending upon the application. Semi-passive (or -active) tags use a small battery for sensing or other functions, but not for data transmission. This project falls under the category of semi-passive, but could potentially be much less expensive than existing semi-passive tags. 13.56 MHz tags are used here as they provide reasonable read distance and operation in the proximity of liquids and metals.